1. Field of the Invention
This invention relates to an optical system for analyzing light from a sample holder. The optical system is particularly suitable for use in a single or multi-channel separation system. The present invention is also directed toward a method of optically analyzing light from a separation system using a spectrograph.
2. Background
Spectrographs are devices for separating electromagnetic radiation into its spectral components. Optical spectrographs can be used for analysis of samples, such as analyzing the chemical composition of nucleic acid samples in order to determine the nucleotide sequence of the sample. Currently, experiments in chemistry and biology typically involve evaluating large numbers of samples. Sequencing of nucleic acid samples is typically time consuming and labor intensive. Therefore, it is desirable that a large number of samples can be simultaneously analyzed. With large scale projects such as the Human Genome Project, it is desirable to increase throughput of nucleic acid sequencing.
Electrophoresis is an increasingly common method of performing analysis, e.g. sequencing, of biological substances in order to increase throughput. Electrophoresis is an electrochemical process in which molecules with a net charge migrate in a solution under the influence of an electric current. Electrophoresis using one or more capillaries which are illuminated by a laser has proven to be useful in analyzing biological substances. Existing systems are typically not well-adapted for imaging large numbers of samples with a small focal ratio and high light collecting ability. Therefore, there is a need for an apparatus and method that maintains a substantially uniform image quality over a large field of view. Preferably, such an apparatus is compact, simple, and reduces focusing problems.